In a capacitive microphone, a sound is converted into an electrical signal by the change of capacitance. In the capacitive microphone, the entirety of the diaphragm constitutes part of the electrode. Thus, downsizing the microphone results in also decreasing the area of the electrode along with the diaphragm. This degrades the sensitivity. On the other hand, the sensitivity is improved by decreasing the gap of the capacitor. However, if the gap of the capacitor is decreased, the gap of the capacitor may be insufficient for high sound volume, and sticking may occur. Sticking is a phenomenon in which the diaphragm remains stuck to the electrode. Furthermore, the capacitive microphone may be designed for high sound volume by including a plurality of diaphragms. However, switching of the diaphragms may be difficult for high frequency sound.